ISPConfig/Postfix - unable to send mail via Outlook

After about a week of changing things and waiting for DNS caches to age, I am able to view my web pages and receive email using Outlook. I am unable to send email to my Yahoo address, however. I get this error message:

It seems that the resolving of domain names does not work correctly on your server. Please kame sure that the nameservers in the file /etc/resolv.conf are reachable from your server.

Click to expand...

This was indeed the problem. First, I had checked resolv.conf during the course of our troubleshooting. I had changed it to match the registrar'snameservers, which I use for my domains. I didn't understand that resolv.conf is the client side of DNS, so to speak. Once I understood that, I checked it again and it had somehow changed back to my own server as nameserver. I commented out the "search" parameter and changed the nameservers to my ISP's nameservers (I found these by going into the status menu of my aDSL modem) and now it works. Another item of note is that I had my domain "associated" to my aDSL account. While attempting to determine the status of my Reverse Zone files, I noted that I was unable to "unassociate" my domain from the ISP account due to an ISP internal server error. I had to contact them and have them manually unassociate the domain, and they did it without messing up my Reverse Zone files.

"This makes me a very, very happy boy." Country Dick Montana -RIP

Thanks, guys. I look forward to more experience with Linux, ISPConfig, etc.